The classical model of the process that maintains intraspecific geographic variation in birds is that phenotypic differences seen in nature reflect genetic adaptations of populations to local environmental conditions and that they are being maintained by natural selection. Wildlife biologists, on the other hand, have usually assumed that, because of the lack of site fidelity among males to breeding areas, many populations of waterfowl are not genetically differentiated. In an attempt to elucidate the genetic and environmental components of geographic variation in reproductive and developmental traits between two populations of Mallard ducks (Anas platyrhynchos), one in southern Manitoba and one in central California, I conducted several experiments. / By monitoring the reproductive performance of wild birds from the two regions reared in common environment under controlled photoperiods in captive conditions, I found that the earlier laying date and lower clutch size observed in nature in the California population are primarily attributable to environmental influences. In addition, there are underlying genetic differences in clutch size between the populations that run counter to differences observed in the wild. Egg size did not differ between populations in the wild or in the common environment. / When reared in a common environment, birds from the wild California population fledged at a younger age than those from Manitoba. These differences disappeared among offspring from captive breeding crosses, reared in a common environment, suggesting that variation in growth rates between the populations in the wild is environmentally induced. When young from eggs taken from the two wild populations were transplanted between localities at different times in the breeding season, some population differences were retained, but much of the variation in development could be attributed to differences in nesting phenology and local environmental conditions. / These results suggest that most of the variation in reproductive and developmental traits between Mallard populations is environmentally induced. However, there is substantial genetic variation in traits within regions. / Source: Dissertation Abstracts International, Volume: 49-08, Section: B, page: 2992. / Major Professor: Frances Crews James. / Thesis (Ph.D.)--The Florida State University, 1988.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77844 |
| Contributors | Rhymer, Judith Margaret., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 96 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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